CODE 45, HEATED O2 SENSOR CKT, RICH EXHAUST INDICATED (GSi): Notes

ECM supplies a voltage approximately .43 volt between ECM terminals D6 and D7. The heater circuit on the O2 sensor is turned on when engine is running. As the O2 sensor heats up, it will begin to send a varying voltage signal to ECM. This voltage will vary from .1-1.0 volts, depending on condition of exhaust gasses in exhaust manifold.

This sensor is like an open circuit and produces no voltage when sensor temperature is less than 600°F (316°C). An open sensor circuit or a cold sensor will cause open loop operation.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Code 45 is set when O2 sensor signal voltage is fixed at greater than .75 volts (750 mV) and with the following conditions:
- TPS greater than 3 percent.
- Codes 21 or 33 not present.
- System is operating in closed loop.
- Coolant temperature at greater than 157°F (69.5°C).
- Integrator block learn value not at 128 counts.
- VSS reading at greater than 3 MPH.